1. Field of the Invention
The present invention relates to a vehicle brake fluid pressure control apparatus and more particularly to a vehicle brake fluid pressure control apparatus which realizes a pressure reducing in a suitable pressure reducing amount for a road surface friction coefficient.
2. Description of the Related Art
Conventionally, there exist vehicle brake fluid pressure control apparatus for controlling the brake fluid pressure in accordance with road surface conditions. As one of them, for example, JP-A-2001-287633 discloses such a vehicle brake fluid pressure control apparatus. In this unit, a configuration is disclosed in which a road surface friction coefficient (also referred to simply as “μ”) is estimated based on a wheel speed, and in the case of a low μ road, a control parameter is compensated so as to increase the pressure reducing amount, whereas in the case of a high μ road, the control parameter is compensated so as to decrease the pressure reducing amount.
However, in case the road surface on which the vehicle is running changes drastically from a low μ road surface to a high μ road surface or a road wheel is temporarily lifted from the road surface due to humps or other irregularities on the road surface, the pressure reducing amount becomes larger than necessary, whereby a drastic change in brake fluid pressure is caused or a pressure increase after the pressure reducing is delayed, leading to a problem that the driver has to feel a deteriorated braking feeling.